What was going on in the united states from 1865-1870?

Congress Adopts the Fifteenth Amendment, The Fifteenth Amendment (Amendment XV) to the United States Constitution prohibits each government in the United States from denying a citizen the right to vote based on that citizen's "race, color, or previous condition of servitude" (i.e., slavery).

Fur traders slowly moved their families closer to the frontier

Explanation:

they wanted to make moolah